Molecular diagnosis of syphilis: the Schaudinn-Hoffmann lymph-node biopsy.

Although serological tests are usually sufficient for the diagnosis of syphilis, they can be unhelpful in identifying the stage of Treponema pallidum infection in various situations. We used fine-needle aspiration of inguinal lymph nodes followed by PCR and Southern blotting to test for treponemal DNA in three patients with suspected secondary or latent syphilis. All three patients were positive by this technique. This approach could serve as a useful new tool for the diagnosis of syphilis in uncertain cases.